CCAMLR

The climate of tile Western Antarctic Peninsula (WAP) region is distinguished by large seasonal and interannual variability and by the occurrence of seasonal sea ice which changes the ocean-atmosphere interface, affects tile surface albedo, and modifies the annual temperature cycle. Air temperature records for several peninsula stations have been examined, and the annual progression of surface air temperatures show an along-peninsula gradient indicative of a contrasting influence of maritime versus continental climatic regimes. WAP temperature records show the largest and most significant warming trends for the Antarctic with mid-winter temperature increases of 3° to 5°C over the past half-century. Increased temperature variability in fall and winter is linked to tile high interannual variability of sea ice coverage. Linear regression analysis shows a significant (99.9%) anti-correlation between air temperature and sea ice extent, even after accounting for serial correlation in the two time series. There are distinct seasonal lead/lag relationships between temperature and sea ice in this region, which underscore the complexity of polar feedback mechanisms. The more than 45 year Faraday air temperature record shows a significant (95% confidence level) correlation with the Southern Oscillation Index (SOI) and coherences between both temperature and sea ice with the SOI suggest teleconnections between the WAP and lower latitudes. This evidence suggests that the WAP area, the focus of the Palmer Long-Term Ecological Research program, is sensitive to climate variability. Consequently, because of strong coupling between temperature, sea ice and the antarctic marine ecosystem, the Palmer LTER is ideally located for the study of ecological responses to global change.

Feeding behavior of Antarctic krill (Euphausia superba) on salps was observed through onboard experiments during 1994/95 Kaiyo Maru Antarctic Ocean research cruise. Feeding rate was more than 1 salp/krill/day. Among 4 items of ethanol extracts; salps, phytoplankton, krill, and polychaets, krill preferred salps best. This evidence implies that the substances extracted from salps were most attractive to krill. The result of our experiment might indicate a tight ecological relationship between krill and salps. Since salps have ability to ingest wide size range of particles, there might also be a possibility of link between microbial loop and krill through salps.

Observations on abundance of by-catch fishes were made during the austral summer months of 1995 (from 30 January to 18 February) on board F/V Niitaka Maru to the north of the South Shetland Islands. Among 78 hauls examined, a total of 97 specimens of fishes belonging to five species, Electrona antarctica, Electrona carlsbergi, Protomyctophum tenisoni, Krefftichthys anderssoni and Notolepis coatsi, were found in 20 trawl catches. Juvenile or adult notothenioid fishes were never found in a random sample of 50 kg of krill. Number of by-catch fishes ranged from 0 to 50 per 100 kg of krill catch and total wet weight of by-catch fishes also ranged from 0 to 248.2 g per 100 kg of krill catch. Abundance of by-catch fishes was higher in krill hauls with the low catch rates.